Intramolecular interactions in vinculin control α‐actinin binding to the vinculin head

Abstract

Using blot overlay techniques we have investigated the interaction of vinculin with α-actinin. We show that an α-actinin binding site is located in the 90 kDa vinculin head and confirm a vinculin binding site in the C-terminal rod of α-actinin, as recently reported by McGregor et al. [(1994) Biochem. J. 310, 225–233]. The isolated vinculin head binds much more strongly to α-actinin than intact vinculin. Using a proteolytic 81 kDa head fragment, we show that vinculin residues 1–107 are required for α-actinin binding. Antibodies directed against vinculin residues 808–850 inhibit the vinculin-α-actinin binding, suggesting that this sequence is directly involved in, or topographically related to, the α-actinin binding site.